Abstract: In this experiment, it was aimed to investigate the effect of exogenous progesterone on in vitro nuclear maturation of bovine oocytes through adding with 10 μg/mL FSH + 10 μg/mL LH (control), 0 ng/mL, 10 ng/mL, 100 ng/mL, and 1000 ng/mL exogenous progesterone respectively into the in vitro maturation medium for bovine cumulus-oocyte complexes (COCs). The germinal vesicle breakdown (GVBD) rate of each group after 8 h using acetic acid-orcein staining, and counted first polarbody (PbI) rate after 22 h were all analyzed. Finally, the blastocyst rate after 7-8 days of in vitro fertilization was also counted. The results showed that, GVBD (75.0%) and PbI (79.6%) rate of the control group were significantly higher than the other ones adding with exogenous progesterone (P<0.05), and blastocyst rate of each group didn’t show significant variation (P>0.05). Therefore, it could be concluded that the exogenous progesterone could not play a role for improving the nuclear maturation of bovine oocytes, it also meant that exogenous progesterone alone could not take the same effect as endogenous progesterone in such kind of processes.